This paper seeks to provide a framework for understanding differential access to medical care in the U.S. population and to suggest ways to achieve equity of access. The framework is provided by a behavioral model of health services utilization which suggests a sequence of predisposing, enabling and illness variables that determine the number of times people will visit a physician. The model is operationalized using a path analytic technique. The data come from a national survey of the noninstitutionalized U.S. population conducted in late 1975 and early 1976. The results suggest services are generally equitably distributed since age and level of illness are the main determinants of the number of services people receive. However, remaining inequities might be reduced by providing people who report no regular source of medical care with a familiar entry into the health service system.